| 荧光猝灭法研究洛克沙胂与腐殖酸的相互作用 |
| 摘要点击 2259 全文点击 1751 投稿时间：2013-11-25 修订日期：2014-01-26 |
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| 中文关键词 结合常数 荧光猝灭 荧光寿命 腐殖酸 洛克沙胂 |
| 英文关键词 association constant fluorescence quenching fluorescence lifetime humic acid roxarsone |
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| 中文摘要 |
| 运用荧光光谱和荧光猝灭滴定方法，研究腐殖酸（HA）与洛克沙胂（ROX）之间的相互作用，考察了HA浓度、pH和温度对ROX与HA之间相互作用强度的影响. 结果表明，HA中的4个峰（Ex/Em=300 nm/480 nm、370 nm/480 nm、420 nm/500 nm、460 nm/520 nm，分别标记为A、B、C、D）与ROX发生了不同程度的猝灭作用，猝灭程度依次为C>B>A>D. 随着HA浓度增加，ROX与峰A所代表官能团结合常数的常用对数值lg K有略微上升，且远大于O2双分子动态猝灭常数的lg K值，表明ROX能与HA中羧基和羰基等官能团发生静态猝灭作用； 在pH值5.00~9.00范围内，ROX-HA体系中峰A的lg K在3.55~3.98 L·mol-1之间波动，且在pH=6.00时达到最大值，这可能是由于pH改变了ROX形态以及HA分子中酚羟基和羧基的构象所致； 在25.0~55.0℃范围内，随着温度上升，lg K值降低，lg K值介于2.65~3.89 L·mol-1之间，这进一步表明ROX与HA中的类FA荧光峰所代表的官能团发生静态猝灭. 瞬态荧光光谱和线性模型拟合分析表明：ROX与HA中峰A、峰B、峰D所代表的官能团均发生单一静态猝灭作用，而与峰C所代表的官能团同时发生静态猝灭和碰撞猝灭作用. |
| 英文摘要 |
| In this study, the methods of fluorescence spectroscopy and fluorescence quenching titration technique were used to identify the interactions between humic acid (HA) and roxarsone (ROX). Effects of HA concentration, pH and temperature on the bonding strength between HA and ROX were investigated. The results showed that the four fluorescence peaks (Ex/Em=300 nm/480 nm, 370 nm/480 nm, 420 nm/500 nm, 460 nm/520 nm, marked as peak A, B, C, D respectively) of HA could be quenched by ROX. The extent of decreases in fluorescence intensities of different peaks was different and followed the order of C>B>A>D. The common logarithm of association constants (lg K) between peak A and ROX increased slightly with the increase of HA concentration and were much larger than the bimolecular quenching constant of O2. It was confirmed that the carboxyl groups and the carboxide groups of HA were quenched statically by ROX. The lg K values fluctuated between 3.55 L·mol-1 and 3.98 L·mol-1 when pH ranged from 5.00 to 9.00, and the maximum value occurred at pH 6.00. It might be resulted from the fact that pH could change the formation of ROX and conformation of phenolic hydroxyl groups and carboxyl groups in HA. The lg K values decreased and fluctuated between 2.65 L·mol-1 and 3.89 L·mol-1 with temperature ranging from 25.0℃ to 55.0℃, which further confirmed the static quenching interaction between HA and ROX. Transient-fluorescence spectrum analyses and liner model simulations revealed that single static quenching was the main mechanism between ROX and the functional groups of fluorescence peak A, B, D in HA, and combined dynamic and static quenching was the main mechanism between ROX and the functional groups of peak C in HA. |
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